Hermetric Refrigerant Compressor

ABSTRACT

The invention relates to a hermetically enclosed refrigerant compressor having a hermetically tight compressor housing inside of which a piston/cylinder unit that compresses a refrigerant operates with a suction valve having a suction opening located in a valve plate of the unit. A suction sound damper having a filling volume is provided on the cylinder head of the piston/cylinder unit and refrigerant flows to the suction valve of the piston/cylinder unit via this suction sound damper. To this end, the suction sound damper has an entry cross-section via which refrigerant flows into the suction sound damper, and a compensation volume is provided, which is connected to the suction sound damper and to the interior of the compressor housing, and inside of which refrigerant oscillates. The compensation volume equals 0.5 to 3 times the displacement of the piston of the piston/cylinder unit.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a hermetically encapsulated refrigerantcompressor, comprising a hermetically sealed compressor housing, in theinterior of which a piston-cylinder unit works which compresses arefrigerant, on the cylinder head of which a muffler is arranged throughwhich the refrigerant flows to the intake valve of the piston-cylinderunit, according to the preamble of claim 1.

STATE OF THE ART

Such refrigerant compressors have long been known and are predominantlyused in refrigerators and cooling shelves. The annually produced numberis accordingly very high.

Although the power consumption of an individual refrigerant compressoris only approximately between 50 and 150 watts, there is a very highpower consumption when regarding all refrigerant compressors usedworldwide, which consumption increases continuously as a result of therapidly progressing development in poorer countries as well.

Any technical improvement made to a refrigerant compressor andincreasing the efficiency thus offers an enormous potential for savingenergy when extrapolating the refrigerant compressors used worldwide.

The refrigerant process as such has long been known. The refrigerant isheated in the compressor by taking up energy from the space to be cooledand finally overheats and is pumped by means of the refrigerantcompressor to a higher pressure level where it emits heat via acondenser and is conveyed back to the evaporator via a throttle wherethere is a pressure reduction and a cooling of the refrigerant.

The largest and most important potential for a possible improvement ofefficiency lies in the lowering of the temperature of the refrigerant atthe beginning of its compression process. Every lowering of the intaketemperature of the refrigerant into the cylinder of the piston-cylinderunit leads to a reduction of the required technical work for thecompression process, as does the lowering of the temperature during thecompression process and, in connection with the same, the push-outtemperature.

In known hermetically encapsulated refrigerant compressors there is astrong heating of the refrigerant on its path from the compressor(cooling space) to the intake valve of the piston-cylinder unit as aresult of the design.

The intake of the refrigerant occurs via a suction pipe coming directlyfrom the compressor during an intake stroke of the piston-cylinder unit.In known hermetically encapsulated refrigerant compressors, the suctionpipe usually opens into the hermetically encapsulated compressorhousing, mostly close to the inlet cross section into the muffler, fromwhere the refrigerant flows into the muffler and from the same directlyinto the intake valve of the piston-cylinder unit. The muffler is usedprimarily to keep the noise level of the refrigerant compressor as lowas possible during the intake process. Known mufflers usually consist ofseveral volumes which are in connection with each other and an intakecross section through which the refrigerant is sucked from thehermetically encapsulated compressor housing volume into the interior ofthe muffler and an opening which lies close to the intake valve of thepiston-cylinder unit.

On the way between the entrance of the refrigerant into the compressorhousing and the intake valve of the piston-cylinder unit there is (asalready mentioned) an undesirable heating of the refrigerant.Measurements have shown that at a refrigerant temperature of 32° C. inthe suction pipe (predetermined by standardized ASHRAE conditions) therefrigerant was heated already in the first muffler volume to atemperature of approx. 54° C. already shortly before entering thecompressor housing. The cause for this undesirable heating of therefrigerant is the fact that the refrigerant freshly flowing from thesuction pipe to the compressor housing is mixed with warmer refrigerantalready situated in the compressor housing. The mixture is principallycaused in such a way that the intake valve of the piston-cylinder unitis merely open over a crank angle range of approx. 180° per cycle andthat refrigerant can be drawn into the cylinder of the refrigerantcompressor merely within this time window. The intake valve is closedthereafter, during the compression cycle. The cold refrigerant has avirtually constant mass flow, even when the intake valve is closed, as aresult of which it flows in from behind into the compressor housing anddwells there and cools the piston-cylinder unit in motion and itscomponents, which again causes a heating of the refrigerant. As a resultof the pressure oscillations during the compression phase, there arefurther flow processes from the compressor housing to the muffler andvice-versa, which thus causes an additional mixing.

In order to prevent this thorough mixture of warm refrigerant from theinterior of the compressor housing with refrigerant freshly coming fromthe evaporator, the outlet of the suction pipe for the refrigerant isplaced in known refrigerant compressors close to the inlet cross sectionof the muffler. This ensures that a relatively low amount of coldrefrigerant can escape from the evaporator into the interior of thecompressor housing. Subsequently, the suction pipe end was configured insuch a way that an intermediate pipe could be inserted into the same. Atthe same time, the intermediate pipe was enclosed by a spiral springwhich rests on the one hand on the entrance of the suction pipe into thehousing and on the other hand on the intermediate pipe in order toachieve a linkage of the suction pipe to the muffler. All these knownefforts to prevent a mixture of the cold refrigerant from the evaporatorwith the heated refrigerant in the interior of the compressor housinghave merely caused a reduction in this mixing, but not a completeprevention.

It is known from WO 03/038280 to directly connect the inlet crosssection of the muffler with the outlet of the suction pipe, so thatrefrigerant coming from the evaporator is guided directly into themuffler without reaching the interior of the compressor housing andwithout being heated there. As a result of the already mentioned factthat the cold refrigerant has a nearly constant mass flow even when theintake valve is closed and flows into the muffler (now via the directconnection), it is then necessary however to provide a compensatingvolume in the muffler in order to compensate a pressure rise in themuffler as a result of the refrigerant that is continuously flowing inand through which refrigerant contained in the muffler can flow out ofthe same again into the compressor housing. During the next intakestroke, the refrigerant situated in the muffler or flowing from thesuction pipe into the muffler is drawn into the piston-cylinder unit viathe intake valve on the one hand, and refrigerant situated in theinterior of the compressor housing is drawn into the compensating volumefor pressure compensation (as a result of leakage from thepiston-cylinder unit and by the mentioned flow-out from the muffler) onthe other hand.

The flow conditions occurring thereby, especially during the overflowinto the compensating volume which would not occur without a directconnection of the suction pipe with the muffler, lead to the likelihoodof increased flow losses.

SUMMARY 0F THE INVENTION

It is therefore the object of the present invention to avoid thisdisadvantage and to provide a refrigerant compressor of the kindmentioned above in which the refrigerant temperature is kept as low aspossible at the beginning of the compression process and thusnecessarily also during the intake into the cylinder of thepiston-cylinder unit, with flow losses during the intake being avoidedto the highest possible extent. It is a further object of the inventionthat the pressure fluctuations occurring in the interior of thecompressor housing and in the muffler and the noise level during theoverflow into compensating volume are kept as low as possible.

This is achieved in accordance with the invention by the characterizingfeatures of claim 1.

By creating a compensating volume with a volume which amounts to 0.5 to3 times the displacement of the piston of the piston-cylinder unit, itis guaranteed that the refrigerant coming from the suction pipe will notreach the compressor housing even when the intake valve is closed andwill mix there with already heated refrigerant. It is guaranteed at thesame time that during the intake process no refrigerant is drawn fromthe compressor housing via the compensating volume into the muffler orinto the cylinder.

In addition, the noise development can be minimized which is caused withthe creation of the compensating volume by the flow processes into thecompensating volume and into the compressor housing, so that there willnot be any disturbing noise for the operator, which is an especiallyimportant feature for household refrigerators. Furthermore, a slightlylarger compensating volume can be produced more easily duringmanufacturing.

In accordance with the characterizing features of claim 2 it is providedthat the smallest cross section in the compensating volume has across-sectional surface area which corresponds to ¼ to ¾ of thecross-sectional surface area of the intake opening. This ensures thatthe pressure difference will become small, the flow losses will decreaseand the noise damping increases to the outside.

According to the characterizing feature of claim 3, the cross section ofthe compensating volume can correspond at most to 1.5 times the pistonhead surface area. This ensures that on the one hand the need for spacefor the compensating volume will not become too high and it is ensuredon the other hand that cold and hot suction gas will not mix or form theboundary layer as described below.

The characterizing features of claim 4, according to which thecompensating volume has a circular cross section and the ratio of thelength of the compensating volume to its diameter is higher than 10,describe a preferred embodiment which leads to especially low flowlosses.

In order to achieve the most compact configuration of the mufflerdespite the additional compensating volume, the characterizing featuresof claim 5 are provided, according to which the compensating volume isformed by a compensating pipe which has a substantially U-shaped crosssection and wraps around the muffler at least partly.

The characterizing features of claims 6 to 9 describe a preferredembodiment of the connection of suction pipe and inlet cross sectioninto the muffler.

The characterizing features of claims 10 and 11 describe two differentembodiments of a hermetically encapsulated refrigerant compressor, inwhich the inlet cross section into the muffler and the transition frommuffler to compensating volume is arranged once separately and. oncecoincidentally. Depending on the need for space in the interior of thecompressor housing, the most advantageous embodiment must be chosen. Inthe case where the inlet cross section into the muffler and thetransition from muffler to compensating volume coincide, a furtherpreferred embodiment according to the characterizing features of claims12 to 14 are provided. This embodiment comes with the advantage that atight connection between suction pipe and muffler is not necessary.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be explained in closer detail by reference to thedrawings, wherein:

FIG. 1 shows a front view of a hermetically encapsulated refrigerantcompressor in accordance with the invention with a compressor housing ina sectional view;

FIG. 2 shows a sectional side view of a refrigerant compressorhermetically encapsulated in accordance with the invention;

FIG. 3 shows a front view of a refrigerant compressor hermeticallyencapsulated in accordance with the invention;

FIG. 4 shows a sectional view of a muffler in accordance with the stateof the art;

FIG. 5 shows a further sectional view of a known muffler;

FIG. 6 shows a sectional view of a muffler in accordance with theinvention with a closed intake valve;

FIG. 7 shows a sectional view of a muffler in accordance with theinvention with an opened intake valve;

FIG. 8 shows an oblique view of the muffler in accordance with theinvention in the compressor housing;

FIG. 9 shows an alternative embodiment of a muffler in accordance withthe invention;

FIG. 9 a shows a further alternative embodiment of a muffler inaccordance with the invention;

FIG. 10 shows an additional alternative embodiment of a muffler inaccordance with the invention;

FIG. 11 shows a detailed view of a hermetically sealed connectionbetween muffler and suction pipe;

FIG. 12 shows a detailed view of an alternative embodiment of ahermetically sealed connection between muffler and suction pipe;

FIG. 13 shows a detailed view of a further alternative embodiment of ahermetically sealed connection between muffler and suction pipe;

FIG. 14 shows a detailed view of a connection between a plastic hosewith a suction pipe;

FIG. 15 shows a detailed view of a connection of a plastic hose with asuction pipe;

FIG. 16 shows a detailed view of a connection of a plastic hose with asuction pipe;

FIG. 17 shows a detailed view of a connection of a plastic hose with asuction pipe;

FIG. 18 shows a detailed view of a connection of a plastic hose with asuction pipe;

FIG. 19 shows an oblique view of an alternative muffler in accordancewith the invention;

FIG. 20 shows a further oblique view of the muffler of FIG. 19 inaccordance with the invention;

FIG. 21 shows a sectional view of the muffler of FIG. 19 in accordancewith the invention;

FIG. 22 shows a further sectional view of the muffler of FIG. 19 inaccordance with the invention.

FIGS. 1, 2 and 3 each show a sectional view through a hermeticallyencapsulated refrigerant compressor, with FIGS. 1 and 3 each showing aview in the direction of arrow A of FIG. 2. A piston-cylinder motor unitis elastically held by means of springs 2 in the interior of ahermetically sealing compressor housing 1.

The piston-cylinder-motor unit substantially consists of a cylinderhousing 3 and the piston 4 performing a lifting movement therein, and acrankshaft bearing 5 which is arranged perpendicular to the cylinderaxis 6. The crankshaft bearing 5 receives a crankshaft 7 and protrudesinto a centric bore 8 of rotor 9 of an electromotor 10. A connecting rodbearing 12 is situated at the upper end of crankshaft 7, through whichthe connecting rod and consequently the piston 4 are driven. Thecrankshaft 7 comprises a lubricating oil bore 13 and is fixed to rotor 9in the area 14. The muffler 16 is arranged on the cylinder head 15,which muffler is to reduce noise development to a minimum during theintake process of the refrigerant.

FIG. 4 shows a sectional view of a muffler 16 according to the state ofthe art. As is already shown in FIGS. 1, 2 and 3, the muffler 16 isarranged on the cylinder head 15 in the interior of the hermeticallysealed compressor housing 1. The refrigerant coming from the evaporator,which refrigerant is cold in comparison with the warm refrigerantsituated in the compressor housing 1, flows via a suction pipe 17 intothe interior of the compressor housing 1 close to the inlet crosssection 18 of the muffler 16 when such a known muffler 16 is used, whereit mixes with the warm refrigerant already situated in the compressorhousing 1 and is heated up and is drawn into the piston-cylinder unitvia the muffler 16.

Mufflers 16 according to the state of the art usually consist of severalsuccessively connected and/or parallel connected volumes V1, V2, V_(n)which are connected via pipes with each other, and of an oil separatoropening 31 at the lowest point. The cold refrigerant flows via suctionpipe 17 into the interior of the compressor housing 1 where as a resultof its configuration a first thorough mixing with the warm refrigerantoccurs which is already situated in the compressor housing 1. Thealready mixed and heated refrigerant then flows through the inlet crosssection 18 into the first volume V1 and then into the second volume V2of the muffler 16 and mixes again with the warm refrigerant alreadysituated both in V1 as well as V2, as a result of which there is arenewed heating of the refrigerant. In these known mufflers, the heatingbetween the outlet from suction pipe 17 and shortly before the intakeopening 24 in the muffler 16 is between 30K and 40K, depending on theoutput of the refrigerant compressor.

FIG. 5 shows a muffler 16 which is also known from the state of the art,namely from WO03/038280, whose inlet cross section 18 is tightlyconnected with the suction pipe 17. The cold refrigerant coming from thesuction pipe 17 is unable to mix with the warm refrigerant situated incompressor housing 1 before it is drawn into the muffler 16. Acompensating volume 21 is connected to the muffler 16, through which thepressure compensation can occur which is required as a result of thedirect connection of the muffler 16 with the suction pipe 17, such thata connection exists both to the muffler 16 as well as into the interiorof the compressor housing. The required pressure compensation leads toflow states of the refrigerant which can lead to the flow losses whichoffset the gain in energy which is achieved by the reduction of therefrigerant temperature at the beginning of the compression phase.

In order to avoid or minimize these flow losses, it is necessary toarrange the compensating volume 21 in such a way that the energy losscaused by the additionally occurring flow losses is lower than theenergy gain achieved by the improved suction. An embodiment of a mufflerin accordance with the invention is shown in FIG. 6. Muffler 16 is shownin FIG. 6 in a sectional view. FIGS. 1, 2 and 3 also show refrigerantcompressors with such a muffler 16 in accordance with the invention. Theinlet cross section 18 of muffler 16 is connected with the suction pipe17 via a schematically shown, hermetically sealed connection 19. A tightconnection 19 can principally be any preferably elastic connection asknown to the person skilled in the art, such as a simple rubber tubewhich needs to be connected in a tight manner with the muffler 16 andthe suction pipe 17. Examples for such connections are shown in FIG. 11to FIG. 18. The muffler 16 in accordance with the invention delimits afilling volume 20 (with the arrangement of several filling volumes beingpossible and done). Adjacent to the muffler 16, a compensating volume 21is arranged which is formed by a U-shaped compensating pipe 34. Theillustrated U-shaped compensating pipe 34 offers the advantage oflimiting a sufficient compensating volume 21 and of requiring onlylittle additional space, and of producing the required flow conditionswhich minimize the mentioned losses. The compensating volume 21 and thecompensating pipe 34 are in connection via a compensating opening 23with the interior of the compressor housing 1 and with the fillingvolume 20 of the muffler 16 via the transition opening 26.

FIG. 6 shows the flow progress of the refrigerant with closed intakevalve by means of arrows, which valve is situated behind the intakeopening 24 of the muffler 16 on the side of the valve plate facing thepiston.

The cold refrigerant flowing from the suction pipe 17 flows via thetight connection 19 to the muffler volume 20 and from there into thecompensating volume 21, as a result of which the warmer refrigerantsituated there is pressed from the compensating pipe 34 via thecompensating opening 23 into the interior of the compressor housing 1.The line indicated with reference numeral 25 symbolizes the boundarylayer which forms between the cold and warm refrigerant.

FIG. 7 shows the same muffler 16 in accordance with the invention, plusflow progress with opened intake valve. In this case, the refrigerant isdrawn in both from the compensating volume 21 and from the fillingvolume 20 and the suction pipe 17. Since the refrigerant in thecompensating volume 21 has a lower temperature than the warm refrigerantsituated in the interior of the compressor housing 1, the mixingtemperature of the refrigerants from the mentioned intake regions islower than the mixing temperature of the refrigerants when usingmufflers known from the state of the art, as a result of which theaforementioned undesirable temperature increase is prevented. As aresult of the inventive feature that the compensating volume 21 has 0.5to 3 times the lifting volume of the piston of the piston-cylinder unit,warm refrigerant is unable to flow from the interior of the compressorhousing into the muffler, which in this embodiment is volume 20. Due tothe fact that the smallest flow cross section 32 has a cross-sectionalsurface area in the compensating volume 21 which corresponds to ¼ to ¾of the cross-sectional surface area of the intake opening 24, it isensured that the pressure difference between muffler 16 and the interiorof the compressor housing 1 is low and at the same time the noisedamping in the interior of the compressor housing is high. Anenlargement of the compensating volume also contributes to this, withthe same being at least half, preferably 0.5 to 3 times the displacementof the piston of the piston-cylinder unit.

At the same time, the flow losses are minimized by the muffler inaccordance with the invention and the refrigerant can easily flow intothe compensating volume or from the same without negatively influencingthe refrigerant process.

For the purpose of better clarity, FIG. 8 shows an oblique view of themuffler 16 in accordance with the invention in the compressor housing 1without the piston-cylinder motor unit.

FIG. 9 shows an alternative embodiment of a muffler 16 in accordancewith the invention, plus compensating volume 21. The compensating volume21 and the muffler 16 are formed by an encasing pipe 34 which encasesthe intake opening 24 on the one hand and opens into the same, andencases an end section of the suction pipe 17 along a section on theother hand. The cold refrigerant flowing from the suction pipe 17 flowsduring the entire intake cycle into the section of the encasing pipe 34forming the filling volume 20 of the muffler 16. In the subsequentcompression cycle, the filling volume 20 of the muffler 16 can no longerreceive any further refrigerant from the suction pipe 17 as a result ofthe closed intake valve, which is why the refrigerant flows back intothe compensating volume 21 which is also formed by a section of theencasing pipe 34 and displaces the warm refrigerant contained thereinvia the compensating opening 23 into the interior of the compressionhousing 1.

As already described in FIGS. 5 and 6, this leads to the formation aboundary layer 25 between warm and cold refrigerant, which layer ismovable depending on the intake cycle. During the next intake cycle,cold refrigerant can be drawn into the cylinder both from the suctionpipe 17 as well as from the compensating volume 21 of the encasing pipe34. The relevant aspect is that the boundary layer does not exceed theline designated with reference numeral 33, which in this embodimentsimultaneously forms the inlet cross section 18 into the muffler 16 andthe transitional opening 26, in the direction of intake opening 24 inorder to prevent a thorough mixture of warm and cold refrigerant priorto the intake process.

At the same time, no cold refrigerant is allowed to be displaced fromthe suction pipe 17 from the compensating volume 21 into the compressorhousing 1. The boundary layer 25 must thus not be displaced behind theline marked in FIG. 9 with reference numeral 23 (compensating opening).Irrespective of the embodiment, a precise adjustment of the volume ofthe compensating volume 21 to the refrigerating output and thus to thedisplacement of the piston-cylinder unit is necessary.

FIG. 9 a shows a further alternative embodiment of a muffler 16 pluscompensating volume 21, in which the muffler 16 is provided with anadditional volume 20 in comparison with that of FIG. 9. In all otherrespects this variant is identical to the one shown in FIG. 9.

FIG. 10 shows an additional alternative embodiment of a muffler 16 inaccordance with the invention. The reference numerals were maintainedaccordingly. As can be seen on the basis of the large number ofdifferent designs, the configuration of the compensating volume canprincipally be chosen freely as long as the features of compensatingvolume 21 in accordance with the invention which is situated upstream ofthe outlet opening of suction pipe 17 are maintained concerning itsvolume and the smallest flow cross section 32. Only then will optimalenergy savings be achieved and the efficiency of the refrigerantcompressor will be improved accordingly.

The question as to how the different compensating volumes 21 and themufflers 16 are arranged is of lower importance as long as the featuresin accordance with the invention are realized and the gas column and theboundary layer 25 is allowed to oscillate in the compensating volume.

The muffler 16 in the embodiment according to FIG. 9 merely consists ofa filling volume 20 which extends in a substantially conical manner, andin the embodiment according to FIG. 9 a of a filling volume 20 aextending in a substantially conical manner and of the filling volume20, and in the embodiment according to FIG. 10 of the volumes V2 and V1.It is understood that the parallel or serial arrangement of additionalvolumes of the muffler 16 is possible at any time and leads to improvedsound-damping properties of the muffler 16.

In the embodiment according to FIG. 9, the compensating volume 21consists of a cylindrical volume. In the embodiment according to FIG. 9a, it also consists of a cylindrical volume and in the embodimentaccording to FIG. 10 of the volumes 21 a and 21 b . The furtherarrangement of the compensating volumes, whether parallel or serial, isobviously possible, with the same contributing to sound damping, like21b for example. The smallest flow cross section 32 in accordance withthe invention can be realized either by a baffle as in FIG. 9, 9 a and10, or by a spatial constriction as shown in FIG. 3. Alternatively, theentire compensating volume 21 can have a constant cross section with thefeatures in accordance with the invention.

FIGS. 11 to 18 show different embodiments of the hermetically sealedconnection from suction pipe 17 to muffler 16 in accordance with theinvention. Only when this connection is actually tight, which means inother words that no warm refrigerant is drawn from the compressorhousing 1 into the muffler 16, the compensating volume 21 will show itsoptimal effect, if it concerns an embodiment as described in FIG. 6 andFIG. 7.

The simplest connection is shown in FIG. 11. In this case, the elasticbellows 19 is merely pushed over the suction pipe 17 without anyadditional fixing, but preferably glued.

FIGS. 12 and 13 show a more complex but stable connection.

In FIG. 12, the wall of the compressor housing 1 comprises an inwardlyfacing nose 28 over which the elastic plastic hose 19 is pushed, whichnose simultaneously protrudes into the inlet cross section 18 of themuffler 16. The plastic hose 19 which can also be arranged as an elasticpipe is enclosed by a spiral spring 27 which ensures required stabilityand fixing. An 0-ring 29 is each arranged both in the area of the nose28 as well as in the area of the inlet cross section 18, which ringensures the required tightness.

In FIG. 13, the muffler 16 also comprises a respective nose protrudinginto the interior of the compressor housing 1.

FIGS. 14 to 18 show different fastening possibilities 30 between elasticconnecting means 19 and suction pipe 17 which can be arranged either asa toothing (FIG. 17, FIG. 18) or as barbs (FIG. 16) arranged on theelastic connecting means, or as simple shoulders (FIG. 14, FIG. 15).

In an embodiment of the compensating volume 21 including muffler 1 asdescribed in FIGS. 9, 9 a and 10, lacks the requirement of such a tightconnection between muffler 16 and suction pipe 17 for the reasons asdescribed above.

FIG. 19, FIG. 20, FIG. 21 and FIG. 22 show a further embodiment of amuffler 16 plus compensating volume 21 as already schematicallydescribed in FIGS. 9, 9 a and 10. The suction pipe 17 is guided close tothe inlet cross section 18 of the muffler 16. The inlet cross section 18is connected by means of a plastic hose 19 tightly with the suction pipe17.

The remaining parts of the refrigerant compressor were not drawn forreasons of clarity in FIG. 19, FIG. 20, FIG. 21 and FIG. 22.

1. A hermetically encapsulated refrigerant compressor, comprising ahermetically sealed compressor housing (1), in the interior of which apiston-cylinder unit works which compresses a refrigerant and comprisesan intake valve with an intake opening (24) arranged in a valve plate ofthe same, with a muffler (16) being provided on the cylinder head (15)of the piston-cylinder unit, which muffler comprises a filling volume(20) and through which the refrigerant flows to the intake valve of thepiston-cylinder unit, and with the muffler (16) having an inlet crosssection (18) through which refrigerant flows into the muffler (16) andwith a compensating volume (21) being provided which is in connectionwith the muffler (16) and the interior of the compressor housing (1) andin which the refrigerant oscillates, wherein the compensating volume(21)is 0.5 to 3 times the displacement of the piston of thepiston-cylinder unit.
 2. A hermetically encapsulated refrigerantcompressor according to claim 1, wherein the smallest flow cross section(32) in the compensating volume (21) has a cross-sectional surface areawhich corresponds to ¼ to ¾ of the cross-sectional surface area of theintake opening (24).
 3. A hermetically encapsulated refrigerantcompressor according to claim 1, wherein the cross-sectional surfacearea of the compensating volume (21) is at most 1.5 times the pistonhead surface area of the piston of the piston-cylinder unit.
 4. Ahermetically encapsulated refrigerant compressor according to claim 1,wherein the compensating volume (21) has a circular cross section andthe ratio of the length of the compensating volume (21) to its diameteris higher than
 10. 5. A hermetically encapsulated refrigerant compressoraccording to claim 1, wherein the compensating volume (21) is formed bya compensating pipe (22) which has a substantially U-shaped crosssection and wraps around the muffler (16) at least partly.
 6. Ahermetically encapsulated refrigerant compressor according to claim 1,wherein the connection of the inlet cross section (18) of the muffler(16) with the suction pipe (17) is an elastic plastic hose (19) made ofPTFE, acrylonitrile, butadiene or fluorinated rubber.
 7. A hermeticallyencapsulated refrigerant compressor according to claim 6, wherein theelastic plastic hose is a bellows.
 8. A hermetically encapsulatedrefrigerant compressor according to claim 1, wherein the suction pipe(17) is provided with barbs.
 9. A hermetically encapsulated refrigerantcompressor according to claim 1, wherein the suction pipe (17) isprovided with latching elements which cooperate with respective latchingelements on the plastic hose (19).
 10. A hermetically encapsulatedrefrigerant compressor according to claim 1, wherein the inlet crosssection (18) and the connecting opening (26) between compensating volume(21) and filling volume (20) are arranged in different sections of themuffler housing.
 11. A hermetically encapsulated refrigerant compressoraccording to claim 1, wherein the inlet cross section (18) issimultaneously the connecting opening (26) between compensating volume(21) and filling volume (20).
 12. A hermetically encapsulatedrefrigerant compressor according to claim 11, wherein the compensatingvolume (21) is formed by an encasing pipe (34) which tightly enclosesthe intake opening (24) and the inlet cross section (18) respectively onthe one hand and encloses the suction pipe (17) of the refrigerant atleast along a section and faces into the compressor housing (1) on theother hand, which suction pipe is connected with the evaporator of therefrigerant compressor and protrudes into the interior of the compressorhousing (1). 13 A hermetically encapsulated refrigerant compressoraccording to claim 12, wherein the suction pipe (17) is guided close tothe intake opening (24)in the encasing pipe (34).
 14. A hermeticallyencapsulated refrigerant compressor according to claim 12, wherein theencasing pipe (34) and the muffler (16) have an integral configuration.